Rock-drill.



J. H. BALDWIN & F. P. DARTH.

ROOK DRILL.

APPLIOATION FILED MAY 12. 1911.

Patented June 23, 1914.

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WITNESSES:

/ ATTRNEY J'. H. BALDWIN z F. P. DARTB.

ROCK DRILL.

APPLICATION FILED MAY 12.1911.

Patented June 23, 1914.

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WITNESSES:

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UNITED STATES PATENT OFFICE.

JAMES H. BALDWIN, OF NEW YORK, N. Y., AND FREDERIC? P- DARTE, OF RIDGEFIELD PARK, NEW JERSEY, .ASSIGNORS T0 BULLES-BALDWIN' ELECTRIC DRILL COMPANY, 0F NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

ROCK-DRILL.

Specification of Letters Patent.

Application filed May l2, 1911..

Patented June 23, 1914. Serial No. 626,773.

To all whom it may concern.'

Be it known that we, JAMES H. BALDWIN, a citizen of the United States, residing at New York, in the county and State of New York, and FREDERIC P. DARTE, a citizen of the United States, residing at Ridgefield Park, in the county of Bergen and State of New Jersey, have invented certain new and useful Improvements in Rock Drills, of which the following is a specification, reference being had to the drawings accompanying and forming part of the same.

This invention relates to rock drills and has for its objectto so construct the parts thereof as to make the same more effective in operation and at the same time simpler in construction. l

It consists briefly in providing a drill with a reciprocating air cushion cylinder with ports in the side thereof and having a piston therein, the blow of the cylinder being coinmunicated to the piston by the instrumentality of the air above and below it. The ports are so arranged or located that the piston has substantially twice the stroke of the cylinder therefore substantially twice the velocity giving greater eiiiciency to the blow. In combination with the mechanism just described we provide a piston stem of such shape that the mechanism for rotating the bit can be slipped over the end to which the piston is connected thus avoiding the necessity of providing grooves at the lower end of the stem which materially weakens the same at the point where strength is so necessary. Suitable connections are shown at the top for operating the air-cushion cylinder, and novel means are provided for connecting the piston, operating in the cylinder, to the stem thereof.

Referring now to the drawings wherein like reference characters indicate the same part in all the views; Figure 1 shows the device partly in cross-section' Fig. 2 is a view of the complete device; F 1g. 3 is a section taken through the piston; Fig. 4 is a top plan view of Fig. 3; Fig. 5 is a section of the device taken on the line V-V of Fig. 1 looking in the direction of the arrows; and Fig. 6 is a section on VIVI of Fig. 1 looking in the direction of the arrows.

The bit or steel (not shown) is carried by a suitable chuck or carrier 1 slidably mount` ed in avguide 2 screw-'threaded into the drill casing 3. Mounted in the casing 3 and above the guide 2 is the air-cushion cylinder 4 and slidable within the latter is a piston 5 having a stem 6, the whole constituting the impact element or hammer. The stem 6 extends through the lower cylinder head 7 and engages with the chuck 1. At its top the `cylinder 4 is connected by a pitman 8 to a crank 9 on the driving shaft, the latter being operatively connected to a gear 10 and this gear in turn connected to a motor 11 through the instrumentality of a pinion 12 and a second gear 13.

14 is a counter balance mounted on the driving shaft.

The piston stem is slightly enlarged at 15 and in this enlargement a groove or grooves 16 are cut of such length that the upper ends thereof ust protrude into the cylinder when the piston is midway between the ends of the cylinder. The grooves extend downwardly as far as desired, at least suiciently to prevent the lower end thereof from contacting with the projections 24 at the limit of upward travel of the stem.

In the lower end of the casing 3 is mounted a disk 19 affording a. bearing for the u per end of the pawl-disk 2() bearing t e pawls 21, the paWl-disk 20 engaging with a corresponding disk 22 to prevent backward movement of the former. This disk 22 as well as the pawl disk 20 is held in place by means of the guide 2 which abuts the lower end of both. It will be noted that the guide 2 is provided with a suitable sleeve 23 fianged at its upper portion in order to maintain itself in position. The anged portion is set down into the guide 2 a short distance thereby providing a seat for the downwardly projecting portion of the disk 20. On the disk 20 are projections 24 adapted to engage the grooves 16 of the stem which prevents a rotary movement of either relative to the other. The grooves are helical in shape and of course the projections or ribs 24 are `shaped to correspond. It willl be noted therefore that as the piston is raised the nut or disk 20 is prevented from turning by means of the pawls 21 enga ng with notches on the annular ring or di 22 being urged into said notches by means of springpressed members 25. The stem of the piston is therefore caused to turn by means of the coperating rib and grooves. As the piston descends the nut turns in the opposite direction, bringing the ratchet into engagement with the next notch. In this way the bit or steel is given a slight turn each time it rises.

The piston 5 is detachably engaged with the stem 6 by means of a. nut 26. This nut Q6 is provided with a series of perforations Q7 and when either is in the proper position will register with one or more perforations or rather depressions 28 whereby a pin 29 can be dropped into the same and lock the piston and nut together and thereby preventing one turning relative to the other. It is understood that the nut 26 is screwthreaded on to the stem. 6. The latter is pre4 vented from turning relative to the piston b v the means shown at 30.

Means are provided at 31 to prevent the cylinder head 7 from turning during the operation of the device. Similar means are also provided at 32 in the guide 2 for an identical purpose. It will also be noted that depressions are formed in the nut 26 for the insertion of a. suitable tool for assembling and removing the said nut.

The exact construction of the piston stem is shown in Fig, 3. As noted above the same is enlarged at 15 leaving the portion above somewhat reduced. A shoulder.' 33 therefore occurs between the reduced and the enlarged portions. A sleeve 34, shown in Fig. 1, and in dotted lines in Fig. 3, is placed over the reduced portion of the stem and rests normally upon the said shoulder 33. Openings 35 are provided in the casing 3 at divers points for introducing oil into the cylinder and casing, and also for introducing air or allowing air under pressure to escape should the same in the casing for any reason be below or above one atmosphere.

In the position of the parts shown in Fig. 1 the cylinder is descending, being just halfway down, to strike a blow. During this movement air is being compressed in the upper part of the cylinder (above the piston) and through the instrumentality of this air above the piston the force of the cylinder is communicated to the piston. The hammer, constituted by the piston and stem,'is thus projected downward. After striking a blow as just described the crank upon which the pitman 8 is mounted together with the cylinder begins to ascend. At rst, as the cylinder rises, the hammer remains stationary; but as the cylinder continues to rise compression of the air below the same becomes sufficient to raise the hammer and the latter is gradually lifted. As the cylinder passes the upper dead center and begins to descend the hammer also begins to fall but floats, as it were, on the air cushion beneath the piston head. The increasing downward speed of the cylinder, however, soon equals and then exceeds the speed of the hammer resulting from gravity. The complete operation just described will then be repeated. It will be noted that side ports 36 in the cylinder 4 are to be provided to relieve the compression (or rarefaction) both above and below the piston at a certain stage.

It will be noted that the interior of the casing is closed to the exterior atmosphere. The cylinder is guided in the casing by suitable guides 37 between which a space or spaces are left which establish free communication between the chamber above and below the cylinder'. Free communication is also established, through ports 36, between the aforesaid chambers and the chambers in the cylinder above and below the piston therein. A valve 38 may also be employed to regulate the force of the impact.

The ports 36 of the cylinder al are arranged midway between the heads thereof, and are for the purpose of establishing a uniform pressure at each stroke of the piston. In other words, if the ports were not provided there would be a tendency for the air to escape from the upper part ot the cylinder and eventually the piston would Contact. at each blow thereof, against the head of the cylinder and cause considerable damage. It. will therefore be noted that as the piston passes the center of the cylinder, traveling in either direction, the chambers behind it will be filled immediately with air. The cut-away portion of the stern of the piston allows the disk 20 to be passed thereover in assembling it which obviates the necessity of cutting a groove in the stem at the lower end thereof, thereby materially weakening the same. The cut-away portion, if it were not for the provision of the sleeve 34, would allow air to escape from the chamber 17 through grooves 16 during the ascent of the cylinder, but by providing the slcevi we ei'ectually prevent such escape of air from the lower part of the cylinder through said grooves in either direction after the piston has passed a certain point of the cylinder in the ascent of thc latter. However, it will be noted that communication will be established between the chambers 17 and 18 through grooves 16 when the piston is somewhat above the center ot the cylinder.

Vile do not limit ourselves to the specific form herein illustrated and described as the same may be changed materially in points of detail without in any waydeparting from the proper spirit and scope of the appended claims.

that we claim is:

1. In a rock drill, the combination with a drill casing of an air cushion cylinder mounted to reciprocate with said casing, a piston movably mounted within said cylinder, a stem for said piston passing through a head of the cylinder and having a grooved portion remote from said piston, means encircling the said portion and having projections coperating with said grooves to rotate the sald stem while the same is reciprccating, said stem having a reduced portion adjacent said piston over which said means is adapted to be assembled, and a sleeve for said reduced portion to prevent the flow of air normally from and into said cylinder through said head.

2. In a rock drill, the combination with a i' drill casing, an air cushion cylinder mounted to reciprocate within said casing, a piston movably mounted within said cylinder, a stem for the said piston passing through a head of the cylinder and having an enlarged grooved portion remote from the piston, means encircling said stem and coperating with said grooves to rotate the said stem, said means adapted to be assembled over the reduced portion of said stem, and a sleeve mounted over said reduced portion to shut between the chambers above and below said c linder, said passages also establishing t rough the ports of the c liudcr free communication between the a oresaid chambers and the interior of said cylinder.

In testimony whereof we aiix our signatures in the presence of two subscribing witnesses.

JAMES H. BALDWIN. FREDERIC P. DARTE. Witnesses:

M. LAWSON Dm, WM. BoHLEBnR.

It is hereby certified that in Letters Patent No. 1,101,387, granted June 23, 1914,

upon the applieaton of James H. Baldwin, of New York, N. Y., and Frederic P. Darte, of Ridgefield Park, New Jersey, for au improvement in Rock-Drills,

au error appears in the printed specification requiring oorreetion as follows: Page 2? line 129, for the word with read withriz; and that the said Letters Patent should beread with this correction therein that the same may conform to the record of the case inthe Patent Oce.

signed and sealed this 7th day of July, A. D., 1914.

R. F. WHITEHEAD,

Acting Commissioner of Patente.

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